A large quantity of plastics has recently been used, and a demand for a paint for use in plastics have been increasing. The paint for plastics is generally required to cure at low-temperature and to provide a coated film superior in hardness, flexibility and acid resistance.
A two-package urethane paint has hitherto widely been used for plastics, because it cures at low-temperature and forms an acid resistant coated film. However, the two-package urethane paint has a problem that a process for coating is complicated and an isocyanate component is toxic. On the other hand, a melamine paint is superior in workability because it is one-package, but it provides a coated film having poor acid resistance.
Japanese Laid-Open Patent Publication No. 63-123471 discloses a paint which forms a coated film having excellent flexibility, but hardness of the coated film is insufficient. Japanese Laid-Open Patent Publication No. 62-140684 discloses a paint which forms a coated film having excellent hardness, but flexibility of the coated film is insufficient.
As described above, there has never been reported a paint which cures at low-temperature and provides a coated film which is superior in hardness, flexibility and acid resistance.